/*******************************************************************************
 * Copyright 2012 Erik Gast
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/
package easyobserving.annotation.processing;

import java.util.HashSet;
import java.util.Set;

import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.RoundEnvironment;
import javax.annotation.processing.SupportedAnnotationTypes;
import javax.annotation.processing.SupportedSourceVersion;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.Element;
import javax.lang.model.element.TypeElement;
import javax.tools.Diagnostic.Kind;

import easyobserving.annotation.Observable;


@SupportedAnnotationTypes("observable.annotation.Observable")
@SupportedSourceVersion(SourceVersion.RELEASE_6)
public class ObservableProcessor extends AbstractProcessor {
	@Override
	public boolean process(Set<? extends TypeElement> annotations,
			RoundEnvironment roundEnv) {
		for ( TypeElement typeElement: annotations ) {
            processAnnotation(roundEnv.getElementsAnnotatedWith( typeElement ), roundEnv);
        }
        return true;
	}
	
	/**
	 * Checks for duplicate observable names.
	 */
	private void processAnnotation(Set<? extends Element> elements, RoundEnvironment roundEnv){
		Set<String> observerNameSet = new HashSet<String>(elements.size());
		for(Element element: elements){
			Observable obs = (Observable)element.getAnnotation(Observable.class);
			if(observerNameSet.contains(obs.name())){
				this.processingEnv.getMessager().printMessage( Kind.ERROR, "Duplicate Observable name \""+ obs.name()+"\"", element );
			}else{
				observerNameSet.add(obs.name());
			}
		}
	}

}
